Note: Descriptions are shown in the official language in which they were submitted.
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~EAIZING HOUSIN EAL
0
The present invention relates to improvements in pillow block assemblies and
more
specifically to a novel seal arrangement for such assemblies.
DACKGROUND ART
Pillow blocks are not new per se and the prior art discloses a variety of
sealing
arrangements for pillow blocks. For example, the KOELSCH Patent Number
4,881.829.
shows a pillow block assembly including a seal chamber located outside the
pillow block
housing. More specifically, the open end of the housing ( 10) mounts a triple
labyrinth seal
(?9) and a cartridge seal ring (35) is mounted in a chamber assembly (34)
adjacent to the
labyrinth seal. Lubricating fluid may be pumped into and out of the sealing
chamber (34). The
roller bearing assembly (?5) is lubricated by grease supplied through a port
(32) which
connects to a passage (33 ) leading to the interior of the housing. The grease
fills the housing
cavity up to the labyrinth seal (29).
Thus the KOELSCH sealing arrangement is rather complex and comprised of many
components. A drawback in the KOELSCH arrangement is the complexity and
expense of
the KOELSCH seal. Further, the KOELSCH seal is non-purgeable, which may cause
a
problem if the housing is overfilled with grease. Additionally, in some
applications which
produce thermal shaft expansion in the axial direction, it has been found that
the contacting
surfaces in the KOELSCH seal tend to separate and consequently there is a loss
of sealing
function. Moreover, by reason of the additional seal housing, the combined
pillow block and
seal housing require a considerable axial width which limits use of a pillow
block and sealing
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arrangement of this type in applications where space requirements are tight.
TESKE United States Patent Number 3,128,104 shows a labyrinth seal for shafts
comprising a ring magnet ( 16) bonded to a flexible corrugated membrane ( 17)
adhesively
bonded to a flexible corrugated membrane ( 17) formed with a solid foot
portion ( 18). The
assembly further includes a supplementary labyrinth seal comprising disks (31
) and (32 ).
Accordingly, the TESKE seal assembly relies on metal to metal contact and by
reason
of its construction and configuration cannot be used in applications where
there is some
amount of axial shaft expansion since shaft expansion would effectively create
forces
disassembling the seal. Note that in Fig. 5 of TESKE, the two rings have to be
moved axially
relative to one another to assemble the seal. The TESKE seal assembly requires
press fits and
ground surfaces to properly mount the seal to the shaft housing assembly.
Further. TESKE
'104 patent may be broadly described as a magnetic seal and therefore there is
no pumping
action associated with the seal. TESKE does not incorporate a directional
aspect whereby.
lubricant can flow in one direction to purge it and the seal has lubricant
retention capabilities in
its normal operating position. Furthermore, the TESKE seal is not purgeable.
TOOLY. United States Patent Number 4.348.067. shows a pillow block housing and
a seal comprising an axial face riding v-ring seal (56) which utilizes axial
contact lip pressure
to provide a seal .at both ends of the housing. This lip seal is located
externally of the housing
and is therefore exposed and in this condition can be easily damaged, for
example, by
ultraviolet degradation or contaminants. Furthermore, the TOOLY design is not
readily
reversible without additional machining of the pillow block housing and
requires the inclusion
of additional elements, such as a washer or use of special tools to prevent
the seal lip from
folding under the labyrinth during assembly of the housing cap.
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DISCLOSURE OF THE INVENTION
The present invention provides a pillow block-seal assembly characterized by
novel
features of construction and arrangemf:nt, providing certain functional
advantages over the prior
art discussed above. To this end, the seal of the present invention is
completely contained within
the pillow block housing and includes a triple ring seal incorporating an O-
ring seal between the
triple ring seal and shaft and a radial lip contact seal located in a
circumferentially extending
chamber between the triple ring seal and pillow block housing wall which is
shaped to form a
labyrinth with the triple ring seal.
This construction provides a number of functional advantages. For example,
existing
pillow block assemblies can easily be retrofitted to incorporate the novel
sealing arrangement of
the present invention. Further, in an assembly utilizing a seal in accordance
with the present
invention, the O-ring not only prevents passage of contaminants or lubricant
under the ring seal, it
additionally forces the ring seal to rotate at the shaft speed and
consequently eliminates shaft wear
and seal rubbing. The base ring seal arts as an inner and outer flinger.
The seal assembly of the present invention is relatively inexpensive comprised
of only few
parts and the width of the overall assembly is not extended beyond the
dimensions of the pillow
block by auxiliary sealing housings or the like. Thus, it can be used in
applications where space
considerations dictate compactness.
Further, it is relatively easy and quick to assemble the seal assembly and no
adjustment is
required due to the fact that the shaft expansion takes place past the O-ring.
The seal chamber
protects the seal elements from relative°ly large sharp objects which
have the capability shredding
the seal or ultraviolet degradation of the rubber characteristic of some prior
seals discussed above,
such as the seal shown in the TOOLY '067 patent. The configuration of the seal
provides good
misalignment capabilities. rChe seal of the present invention offers
interchangeability between
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grease and other lubricants. In one configuration, the grease is purgeable and
in another the seal
can easily be reversed for lubricant retention when the application so
requires.
The present invention provides a labyrinth seal arrangement particularly
adapted for
pillow blocks characterized by novel features of construction and arrangement
which can be
readily adapted to retrofit existing conventional standard pillow block
assemblies. The present
invention also provides a novel seal arrangement which minimizes shaft wear.
The present
invention also provides a novel seal arrangement particularly adapted for use
in pillow block
applications wherein the overall width of the assembly is maintained at a
minimum thereby
facilitating use of a pillow block in applications where conventional extended
seal assemblies
cannot be used because of their bulk. Further, the present invention provides
a novel seal
arrangement for pillow blocks which is comprised of relatively few parts and
is so that the
manufacture and assembly thereof is relatively simple and inexpensive. Still
further, the present
invention provides a novel seal assembly which is completely housed within the
pillow block
housing so that the sealing elements are protected from external elements that
can cause damage,
such as relatively large sharp objects and particles and ultra violet rays.
The present invention also
provides a novel seal arrangement for pillow blocks which allows for slight
misalignment of the
various elements comprising the pillow block and mounting assembly. The
present invention also
provides a novel seal assembly for pillow block assemblies wherein the parts
are interchangeable
so they can be used in grease lubricant applications and provides a means for
purging and by a
simple reversal of one of the elements can be adapted for lubricant retention
where a lubricant
fluid is the lubricant choice.
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BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects of the present invention, as well as various details
of the operation
and construction thereof, are hereinafter more fully set forth with reference
to the accompanying
drawings wherein:
5 Fig. 1 is a front elevational view of a pillow block assembly incorporating
a novel seal
arrangement in accordance with the present invention;
Fig. 2 is a sectional elevational view taken on lines 2-2 of Fig. 1;
Fig. 3a is an enlarged fragmentary sectional view of the detail and designated
Fig. 3a
encircled by the broken line circle in Fig. 2:
Fig. 3b is similar to Fig. 3a wi~:h the lip of the sealing ring reversed;
Fig. 4 is a sectional view similar to Fig. 2 showing a modified pillow block
and seal
assembly in accordance with the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to the drawings, and particularly to Figs. 1 and 2 thereof,
there is shown a
pillow block housing incorporating novel seal means in accordance with the
present invention.
The assembly comprises a housing base (10) having a laterally extending
mounting flange (12) for
mounting the pillow block housing on a machine component or the like. The
assembly further
includes a housing cap portion (14) which seats on the base (10). The cap
portion (14) and base
(10) are secured in the assembled relationship by elongated bolts (16) which
engage through
bosses ( 18) on opposite sides of the c;rp portion ( 14) which align with
tapped openings in bosses
(20) formed integrally with the base (10).
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The housing cap portion ( 14) and base ( 10) as illustrated in Fig. 2 are
hollow and ha~~e
semi-circular openings defined in opposing end walls through which a shaft
(36) extends.
More specifically. l:he cap portion has a semi-circular cutout (24) in one end
wall (28) and the
base portion (10) has a semi-circular opening (26) in a complementary end wall
(3?). The
6 semi-circular openings (24) and (26) are aligned to define a generally
circular opening at this
end of the pillow block housing. The opposing end walls (30) and (34) of the
cap portion ( 14)
and base ( 10) respectively are likewise provided with a central opening
designated by the
reference numerals (24x) and (26x).
There is shown in Figs. 2 and 4 a double row spherical bearing generally
designated by
the numeral (40). which rotatably supports the shaft (36) in the housing. The
bearing (40)
comprises the usual inner and outer rings (42) and (44) respectively and a
complement of
barrel shaped rollers (45) arranged in two rows in the annular space between
the rings. The
outer ring (44) seats in semi-circular recesses (48) and (50) in the cap
portion ( 14) and base
( 10) respectively which are radially aligned to form a continuous
circumferentially extending
seat (51 ) for the outer ring (44) of the bearing. The width W of the seat (5
I ) is preferably
greater than the axial width Wb of the bearing to accommodate bearings of
different sizes and
allow for thermal expansion of shaft (36).
In the assembled relation, a stabilizing ring (56) engages in the seat (51 )
to locate the
outer ring of the bearing in a fixed stable position in the bearing seat. The
inner ring (42) of
the bearing is mounted to the shaft by a wedge tapered sleeve (54) having an
outer tapered
surface (54x). The tapered sleeve (54) is threaded at one axial end to
accommodate a nut and
lock washer (55) which presses the tapered bore (42x) of inner ring (42) of
the bearing against
the taper to (54x) clamp the inner bearing ring relative to the shaft.
The inner ring (42) may be mounted directly to the shaft if desired. Lubricant
ports
(60) and (62) are provided in the cap portion ( 14) which are tapped to
facilitate application of
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a grease fitting nozzle to supply a charge of grease to the interior pillow
block housing and the
bearing mounted therein. In circulating oil applications, the fittings (60)
and (62) receive
threaded oil inlet fittings to conduct oil lubricant to the bearing.
In accordance with the present invention, seal means is provided at opposite
axial ends
of the pillow block housing, the details of which are best shown in Fig. 3a.
The seal
arrangement in accordance with the present invention consists broadly of a
labyrinth seal Sl. a
O-ring seal S~ and a lip seal characterized by a novel arrangement providing
the functional
advantages discussed above.
Thus the labyrinth seal S~ comprises a triple ring member generally designated
by the
numeral (62) which is mounted on the shaft (36) and has circumferentially
extending radially
outwardly directed flanges (64) and (66) at opposing axial ends and an
intermediate flange
(68) of a shorter radial height Ha than the radial height Hb of the terminal
end flanges (62)
and (66). The flanges are axially spaced as illustrated to define
circumferentially extending
channels (70) and (72) between the end flanges and intermediate flange (68).
The inner end wall of the cap portion ( 14) is of a predetermined
configuration
complementing the flange and channel arrangement of the labyrinth seal member
(63 ) to form
a serpentine generally "W" shaped labyrinth path P between the members as
shown in Fig. 3a.
Thus, the end wall (28) has a pair of depending circumferentially extending
ribs (74). (76)
defining therebetween a circumferential channel (77) and are spaced apart a
predetermined
distance to engage in the grooves (70) and (72) formed in the labyrinth seal
member (62). The
ribs (74) and (76j are spaced axially inwardly from the inner and outer side
surfaces (28a) and
(28b) of the end wall (28) to define land areas (81 ) and (83 ) overlying the
flanges (64) and
(66). The circumferentially extending space (77) between the ribs (74) and
(76) straddles the
intermediate flange (68) of the labyrinth seal member (62) and is of a radial
depth Dr to define
with the intermediate flange (68) a rather substantial chamber (77) for a
contact type sealing
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element (84) which has a body portion (86) filling the width of the chamber
and a radially
inwardly directed lip (88) projecting from one axial end of the body portion
which engages the
outer peripheral sL~rface ofthe intermediate flange (68).
A circumfe~rentially extending groove (91 ) is formed in the inner bore
surface (93) of
the sleeve member (62) defining an annular chamber for an O-ring seal (90).
The groove is
aligned radially with the intermediate flange member (68) as shown in Fig. 3a.
The inner peripheral surface defining the semi-circular opening (26) in the
base ( 10) is
of a similar configuration to form with the labyrinth seal member (62) the
same type of
serpentine generally "W" shaped path P described above. Accordingly, the
elements
comprising the ribs and channels are given the same reference numerals with
the subscript "b".
The lip seal (84) as shown in fig. 2 faces outwardly and is adapted for grease
lubricated
bearings to facilitate purging. More specifically when it is desired to
recharge the housing
cavity with new grease, the fitting is simply applied to the housing part (60)
and the pressure
causes the sealing lip (88) to deflect outwardly and permit escape of the old
grease when
charging with the new and expel contaminants which have entered the labyrinth.
The lip seal
(88) may be reversed for retaining lubricant in the bearing housing when using
oil type
lubrication systems.. Fig. 3b. shows reversal of the lip seal for applications
where oil lubricant
is used and the various referenced numerals applied previously are the same.
Further, the O-ring seal (90) prevents passage of contaminants or lubricant
under the ring seal
and frictionally drives the ring seal to rotate at shaft speed.
Summarizing the above briefly and with reference to Figs. 3a and 3b, the
configuration
in 3a is particularly adapted for grease lubrication applications and in this
instance. the radially
inwardly directed lip (88) presses against the seat (68a) so that internal
pressures deflect the lip
v
(88) outwardly away from the seat (68a) and create an opening for purging the
grease when
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desired. More specifically, new grease entering the port (62) under pressure
displaces the old
grease causing an increased axial pressure on the outer peripheral face (88a)
of the lip (88) to
produce the deflection action described. By contrast in Fig. 3b, the lip (88)
is directed
inwardly toward the interior of the bearing and therefore any lubricant
pressure against the
inner peripheral face (88~) of the lip, tends to seat the lip more firmly
against the seat (68a)
and is used primarily in oil lubrication applications. In some instances where
the shaft is
vertically oriented, the Fig. 3b configuration is used in grease applications
to prevent purging
which may occur by gravitational forces on the grease lubricant.
The arrangement of the present invention provides advantages over press fit
applications such as in the TESKE and TOOLY arrangements. Press fits typically
require
special or more precise machining and therefore add to the expense of
manufacturing and
assembling the components. The present invention also has an advantage over
the prior art
discussed above allowing for any needed axial movement of the shaft for
example, due to
thermal expansion and other forces in the system.
The O-ring seal So has a sliding fit on the shaft. This eliminates wear of the
parts and
extends the life.
Fig. 4. shows a modified embodiment of the present invention which is useful
in
applications where the bearing is free to float to a limited degree in the
bearing housing. This
allows for a controlled axial play in the system. Similar parts are designated
by the same
reference numerals. In this instance, however, the shaft does not extend
entirely through the
housing and an end plate (97) in the nature ofa disk with an O-ring seal (99)
engages in a
groove (101) between the flanges (74) and (76).
Even though particular embodiments of the present invention have been
illustrated and
described herein, it is not intended to limit the invention and changes and
modifications maybe
made therein within the scope of the following claims.
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